Origin

Latin elementum ‘principle, rudiment’ is the source of element. In medieval times people thought that everything was made up from four elements: earth, air, fire, and water. They also believed that each kind of living creature had a natural affinity with one of these elements: most commonly these were air and water, although the salamander, for example, was supposed to live in fire. From this idea came that of a person's natural or preferred environment, and of being in your element if you are doing something that you love. The element was sometimes used specifically to mean ‘the sky’, and the elements became a term for strong winds, heavy rain, and other kinds of bad weather. Elementary is particularly associated with Sherlock Holmes saying ‘Elementary, my dear Watson’, although the phrase is not actually found in any of Sir Arthur Conan Doyle's books. Holmes did certainly say ‘My dear Watson’, and he said ‘Exactly, my dear Watson’; but the famous phrase does not appear until 1915, in P. Smith, Journalist by P.G. Wodehouse.